An experiment on actinide partitioning from real high level waste (HLW) was performed in a continuous process by extraction with diisodecylphosphoric acid (DIDPA) using a battery of 12 centrifugal extractors installed in a hot cell. The HNO3concentration of the HLW was adjusted to 0.5 M by dilution. The extraction section had 8 stages, and H2O2was added to extract Np effectively. After extraction, Am and Cm were back-extracted with 4 M HNO3in 4 stages and Np and Pu were stripped with 0.8 M H2C2O4in 8 stages.